Wound treatment device for attachment to skin

ABSTRACT

A non-contact wound treatment device having a flexible portion to accommodate patient motion without peeling off. A removable heater may be included which is suspended above the wound to define a treatment volume, where the heater heats the treatment volume to help treat the wound.

CROSS REFERENCE TO RELATED CASES

This is a continuation application of U.S. patent application Ser. No.08/836,066, filed Apr. 29, 1997, now U.S. Pat. No. 6,013,097 which isthe National Stage Application of International Application Serial No.PCT/US95/15197, filed on Nov. 21, 1995, which is a continuation-in-partof, and claims priority from, U.S. patent application Ser. No.08/342,741 filed Nov. 21, 1994, now U.S. Pat. No. 5,817,145.

TECHNICAL FIELD

The invention relates to a wound treatment device for covering and insome applications heating skin lesions, surgical wounds and the like.

The wound treatment device includes a wound cover and optionally adetachable wound heater which provide a non-contact wound treatmentvolume over the wound area.

The invention also relates to methods for making and using the woundtreatment device.

BACKGROUND OF THE INVENTION

One traditional method of treating a wound involves the placement of asterile gauze over the wound area and holding the gauze in place with anadhesive tape. This type of wound dressing has numerous shortcomings.The wound is not fully isolated from the air and can exchange bacteriawith the environment. The gauze can adhere to the wound itselfinterfering with the healing process which is undesirable. Thistraditional form of bandage does not control the thermal environment ofthe wound which is also undesirable.

Although some forms of wound heaters and non-contact wound coverings areknown from Veilhan Fr. 1,527,887 (1969) they are not generally acceptedfor several reasons. For example, wound coverings which include a rigidenclosure forming a cavity that covers the wound are usually adhesivelyattached to the skin of the patient with a relatively inelasticmaterial. As a result the wound covering is unable to accommodatepatient motion. Consequently patient motion will cause the rigid woundcovering to “peel-off” of the patient's skin. The traditional solutionto this problem has been to use a more aggressive adhesive tape or thelike to more firmly attach the wound covering to the skin. This solutionto the problem results in an uncomfortable bandage.

The traditional wound covering does not permit close control over thetemperature of the wound area. Prior art heated bandages which rely on anon-contact enclosure may use point source type heaters which result invariations in radiant heat flux depending on the location of the heaterwithin the enclosure. Therefore there is a need for a non-contactbandage which can be used to control the environment of the wound andwhich may be reliably and comfortably attached to the skin.

SUMMARY OF THE INVENTION

The wound treatment device 10 of the present invention has an upperwound covering surface displaced above the patient's skin surface, andan attachment surface lying generally in the plane of the patient'sskin. Together these two surfaces define an enclosed non-contact volumeover the wound treatment site.

The wound treatment device 10 may be divided into three separate partsfor the purpose of description. These parts are an attachment portion12, a wound treatment portion 14, and a transition portion 16. Eachportion is designed to serve a separate function.

The attachment portion 12 is used to connect the wound treatment device10 to the skin of a patient. The attachment portion 12 will usually beformed as an annular attachment rim. An adhesive will typically beplaced on the attachment rim to couple the wound treatment device 10 tothe patient. The attachment portion 12 lies near the patient's skin anddefines a so called first plane.

The wound treatment portion 14 of the wound treatment device 10 isillustratively an assembly which includes a standoff 15 which risesabove the patient's skin surface, and a wound cover 20 which spans theopen portion of the standoff 15. The standoff 15 helps to define thevertical extent or dimension of the wound treatment device 10 and helpsto define the location of a second plane which is used to describe thegeometry of the device. Thus the wound treatment portion 14 includes astandoff 15 and a wound cover 20 which together define both a woundtreatment volume 24 and a wound treatment area 26.

The wound treatment volume 24 is located over the surface of the wound.The atmosphere in this wound treatment volume 24 can be controlled bythe wound treatment device 10.

In use the wound treatment area 26 is defined on the patient surface 18under the wound treatment portion 14, and will typically be centeredover the lesion or wound.

The transition portion 16 connects the attachment portion 12 to thewound treatment portion 14. This transition portion 16 improves thecomfort and utility of the wound treatment device when the patient movesand stretches the wound treatment device 10. This stretching causes thetotal projected area of the wound treatment device 10 to increase andthe shape of the wound treatment device 10 to change. In practice, thebulk of the patient motion is accommodated by the compliance of thetransition portion 16. As a consequence, the transition portionprojected area 17 increases. The standoff of wound treatment portion 14rests gently on the patient's skin and it may twist to accommodatepatient motion thus producing a device which conforms to the contour ofthe patient's body. However since the standoff can slide along thepatient's skin there is no substantial change in the projected woundtreatment area 28 due to patient motion. During patient motion theattachment portion 12 remains affixed to the surface of the patient andis easily deformed by body motion because of its relatively small area.Consequently the attachment portion projected area 40 may undergo aslight increase in area as the attachment portion 12 moves with theunderlying skin. Throughout this motion the second shaped surface issupported above the patient's skin surface and can be used to support adetachable heater 32 which can heat the wound surface. A switch may alsobe provided to reduce power supplied to the wound treatment device 10 ifthe device is crushed in to contact with the wound.

BRIEF DESCRIPTION OF THE DRAWINGS

The various figures of the drawing depict illustrative and exemplaryforms of the wound treatment device 10. Throughout the several views,identical reference characters represent similar or equivalentstructures wherein:

FIG. 1 is a perspective view of a first embodiment of the woundtreatment device;

FIG. 2 is a schematic view of projected areas;

FIG. 3 is a schematic view of projected areas;

FIG. 4 is a perspective view of a detachable heater in combination witha first embodiment of the wound treatment device;

FIG. 5 is an exploded view of the first embodiment of the woundtreatment device;

FIG. 6 is an exploded view of the second embodiment of the woundtreatment device;

FIG. 7 is a perspective view of a heater system;

FIG. 8 is an electrical schematic of a pressure sensitive switch for aheater system;

FIG. 9A is an exploded view of a pressure sensitive switch incorporatedinto a wound treatment device;

FIG. 9B is a view of a portion of the pressure sensitive switch;

FIG. 10 is a perspective view of a passive heater embodiment of thewound treatment device;

FIG. 11A is a schematic drawing depicting an alternate geometry for thetransition portion;

FIG. 11B is a schematic drawing depicting an alternate geometry for thetransition portion;

FIG. 11C is a schematic drawing depicting an alternate geometry for thetransition portion;

FIG. 11D is a schematic drawing depicting an alternate geometry for thetransition portion;

FIG. 12A is a schematic drawing depicting functional relationshipsbetween several elements of the invention;

FIG. 12B is a schematic drawing depicting functional relationshipsbetween several elements of the invention;

FIG. 13A is a schematic drawing depicting functional relationshipsbetween several elements of the invention;

FIG. 13B is a schematic drawing depicting functional relationshipsbetween several elements of the invention;

FIG. 14A is a schematic drawing depicting functional relationshipsbetween several elements of the invention;

FIG. 14B is a schematic drawing depicting functional relationshipsbetween several elements of the invention;

FIG. 15 is a perspective view of an alternate version of the woundtreatment device;

FIG. 16 is a perspective view of an alternate version of the woundtreatment device;

FIG. 17A is a perspective view of an alternate version of the woundtreatment device with a heater;

FIG. 17B is a perspective view of an alternate version of the woundtreatment device with a heater;

FIG. 17C is a perspective view of an alternate version of the woundtreatment device;

FIG. 18 is a perspective view of an alternate version of the woundtreatment device with a heater;

FIG. 19A is a perspective view of an alternate version of the woundtreatment device with a heater;

FIG. l9B is a perspective view of an alternate version of the woundtreatment device with a heater;

FIG. 20A is a perspective view of an alternate version of the woundtreatment device with a heater;

FIG. 20B is a perspective view of an alternate version of the woundtreatment device with a heater;

FIG. 21A is a perspective view of an alternate version of the woundtreatment device with a heater;

FIG. 21B is a perspective view of an alternate version of the woundtreatment device with a heater;

FIG. 22A is a perspective view of an alternate version of the woundtreatment device with a heater; and

FIG. 22B is a perspective view of an alternate version of the woundtreatment device with a heater.

DETAILED DESCRIPTION

FIG. 1 is a perspective view of the wound treatment device 10 applied toa patient's skin surface 18. A coordinate system 11 is depicted on thepatient's skin surface 18 and it defines X, Y and Z directions. Theattachment portion 12 is formed as an planar rim or flange. This elementis attached to the patient's skin with an adhesive and it lies in afirst XY plane. In this first embodiment of the wound treatment device10 the transition portion 16 is integrally formed with the attachmentportion 12. The transition portion 16 rises vertically from the skinsurface in the Z direction to connect to the wound treatment portion 14.In this embodiment the wound treatment portion 14 has a transparentplanar wound cover 20 which allows one to see the wound treatment area28. The wound cover 20 is supported above the first XY plane by a foamring standoff 15. The planar wound cover 20 lies in a second XY planethat is vertically displaced along the Z-axis by the foam ring standoff15 from the first XY plane. The wound cover 20 and foam ring standoff 15together form the wound treatment portion 14. The region over the woundtreatment area 28 is called the wound treatment volume 24.

In this figure the wound treatment device 10 has been applied to apatient's skin and is in a relaxed state. In this unstressed state onecan see the outer periphery 22 of the attachment portion 12. The innerperiphery 23 is shown by a crease in the structure where it connects tothe transition portion 16.

FIG. 2 and FIG. 3 should be considered together. Together they show theinfluence of patient motion on the wound treatment device 10. Both FIG.2 and FIG. 3 are top views of the wound treatment device 10 of FIG. 1with the various portions of the wound treatment device 10 projectedonto the first XY plane.

In FIG. 2 the wound covering is shown in a relaxed and un-stretchedstate having a nominal total projected area 27. The projected woundtreatment area 28 is shown at the center of the wound treatment device10. The outline of the foam ring standoff 15 may be seen as thecrosshatch area bounded by exterior perimeter 25 of the foam ringstandoff 15, and the interior perimeter 26 of the foam ring standoff 15.The transition portion projected area 17 is shown in the figure boundedby the inner periphery 23 of the attachment portion 12, and the interiorperimeter 26 of the foam ring standoff 15. The attachment portionprojected area 40 is shown as the cross hatched area bounded by theouter periphery 22 and the inner periphery 23 of the attachment portion12.

FIG. 3 shows the wound treatment device 10 stretched along the X-axis bypatient motion. In comparison to FIG. 2 the overall or total projectedarea 27 of the wound treatment device 10 has increased. The attachmentportion projected area 40 has increased slightly as the attachmentportion moves with the underlying skin. The projected wound enclosurearea 28 is essentially unchanged in area since in this embodiment thefoam ring standoff 15 is free move against the skin. The largestpercentage area change occurs in the transition portion projected area17. As the wound treatment device 10 deforms in response to patientmotion the transition portion is compliant and pays out materialpermitting the majority of the total projected area 27 increase to beaccommodated primarily by the transition portion projected area 17.

FIG. 4 shows a detachable heater 32 positioned for insertion into apocket formed by pocket cover 21. Pocket cover 21 is bonded to the woundcover 20 and is sized to retain the heater 32. The foam ring standoff 15and wound cover 20 serve to stabilize the shape of the wound treatmentdevice while the transition portion accommodates patient motion.Consequently the heater is reliably and comfortably positioned above thewound surface. In general it is desirable to use a planar heater 32which has a constant heat output per unit area. This form of heaterresults in a more uniform flux of radiant energy applied to the wound.And the amount of heat supplied to the wound area is largely independentof the height of the heater 32 above the wound surface.

FIG. 5 is an exploded view of the first embodiment of the woundtreatment device 10. The attachment portion 12 and transition portionmembrane 36 are formed as a unitary composite shell 38. The compositeshell may be vacuum formed from closed cell polyolefin foams such asVolara-6AS, which is a polyethylene material as sold by Illbruck Inc. ofMinneapolis, Minn. It should be apparent that many other materials maybe substituted within the scope of the invention. The foam ring standoff15 may be die cut from foam sheeting of a reticulated polyurethane foam.The absorbency of the foam as well as its mechanical properties can betailored to the particular wound treatment application. For example, thefoam standoff may be impregnated with a medicament such as anantibiotic; antifungal; or antimicrobial material. It may also bedesirable to supply a deodorant material or nitric oxide releasingmaterial from the foam standoff. The wound cover 20 and wound pocket 21may be made from a thin film of polyethylene. In general, the compositeshell should be sufficiently self supporting so that when the woundtreatment device 10 is removed from its release liner the woundtreatment portion 14 is held up or supported by the shaped flexion jointof the transition portion membrane 36, and some effort is required toevert the composite shell and turn it inside out. This behavior definesthe self supporting feature which causes the foam ring standoff 15 tolie gently against the skin even when the wound treatment device 10 isupside down. For larger wound coverings it may be desirable to apply atacky adhesive to the patient contact surface of the standoff.

FIG. 6 is an exploded view of the second embodiment of the woundtreatment device 10. The attachment portion 12 and transition portionmembrane 36 are formed as a unitary composite shell 38. In thisembodiment the wound treatment volume is formed by a serrated cupstandoff 34. This member made be made from a more rigid polymericmaterial such as polyethylene or the like. The serrations typified byserration 44 permit the serrated cup to flex and accommodate patientmotion. This embodiment shows a release liner 42 coupled to theattachment portion 12 of the composite shell 38 with an adhesive 46.Inthis embodiment the pocket cover 21 is bonded to the composite shell 38.

FIG. 7 depicts a power supply to permit the ambulatory use of the heatedversions of the wound treatment device. A collection of battery cellsmay be wired together to form the power supply 48 which may beconveniently attached to a belt 49. A suitable cable 50 may be used toconduct power to the heater 32. In many instances it may be desirable tocut off power to the heater if the wound treatment device is collapsedagainst the wound to prevent overheating of the wound surface.

FIG. 8 shows a schematic representation of a touch switch which may beincorporated directly into the detachable heater 32. The heater 32includes a continuous resistive heating coil 51. A conductive membrane52 is arranged near the coil 51 so that it may “short out” segments orportions of the coil 51. In use power to the coil is completely turnedoff by pressure applied to the entire touch sensor 53.

FIG. 9A shows an exploded version of the heater 32 which incorporates atouch switch of the type described schematically in FIG. 8. The switchcover 45 has a conductive membrane which is located over the conductivepattern of the heating coil 51. It is held in position with an adhesiveband 54. FIG. 9B shows the underside of the switch cover 45 showing anumber of discrete insulation bumps typified by bump 47 which serve tospace and support the conductive membrane 52 above the heating coilpattern 51. Pressure supplied to the switch cover inactivates the heatercoil 51.

FIG. 10 shows a an accessory device 55 or cover. This may take the formof a passive heater with a reflective surface facing the wound. Theaccessory device may also take the form of a mapping grid where a gridwork of lines is positioned on a transparent card to permit tacking ofthe wound healing process.

FIG. 11A through FIG. 11D should be considered together. These drawingsfacilitate a description of connection structures of the invention andrepresent several alternative connection geometries. In general toaccommodate patient motion the transition portion pays out storedmaterial to increase the projected area of the transition portion. Eachof these drawings represents a mechanical schematic cross section of awound treatment device 10 in the XZ plane. In each figure the woundcovering is in the relaxed state.

FIG. 11A shows a schematic view of a ring standoff 15 extending from afirst plane 56 to a second plane 58. The transition portion 16 has atransition portion membrane 60 which is coupled to the attachmentportion 12 by a first flexible connection 62 formed at the intersectionof the attachment portion 12 and the transition portion 16. Thetransition portion membrane 60 is connected to the treatment portion ata second flexible connection 64 which is formed at the intersection ofthe transition portion 16 and the wound treatment portion 14. The woundtreatment portion 14 is generally a cylindrical cup shaped structuredefining a wound treatment area on the patient skin surface. The minimuminterconnection distance 66 is depicted as a dashed line extending fromthe first flexible connection 62 to the second flexible connection 64.The length of this minimum interconnection distance 66 can be used tocharacterize the “length” of the transition portion membrane 60. Formany embodiments of the invention the length of the transition portion16 between the first flexible connection 62 and the second flexibleconnection 64 is greater than the length of the straight line drawnbetween these points. This relationship is true for many embodiments ofthe wound treatment device when they are in the relaxed or unstressedposition. It should be noted that the vertical distance between thefirst plane 56 and the second plane 58 represents a minimum value forthe minimum interconnection distance 66. In the XY plane the firstflexible connection 62 forms a first perimeter 61 and a second perimeter63. In the embodiment depicted in FIG. 11A the first perimeter 61 islarger than the second perimeter 63.

FIG. 11B is a mechanical schematic diagram which represents a crosssection of another embodiment of the wound treatment device 10 with analternate connection geometry. In this drawing the wound cover 20extends radially beyond the wound treatment volume 24 so that the secondperimeter 68 is greater than the first perimeter 71. This generates areflex transition portion 74 construction which may be adopted toincrease the “length” and amount of material in the reflex transitionportion 74.

FIG. 11C shows a construction where the first perimeter 76 and thesecond perimeter 78 have approximately the same value and are bothconcentric with the axis 90. This construction can produce an undulatedtransition portion 77. Once again the length of the undulated transitionportion 77 exceeds the length of the line 65 between the first perimeter78 and the second perimeter 76.

FIG. 11D shows a hemispheric shell 70 as the wound treatment portion 14.In this embodiment the second perimeter 80 is a single attachment pointgenerally concentric with the axis 90. In this embodiment the firstperimeter 81 has a length which greatly exceeds the second perimeter 80length. This construction forms a hemispheric transition portion 79which has a length which exceeds the linear distance between the secondperimeter 80 and the first perimeter 81 along the line 85.

Although the various geometries vary in detail it is preferred to formthe transition portion from a resilient material which is generallyself-supporting, yet sufficiently flexible so that it acts as acompliant hinge mechanism. This flexibility prevents the transfer ofshearing force from the wound treatment portion 14 to the attachmentportion 12 of the wound treatment device 10 and visa versa. With thegeometries set forth in FIG. 11A through FIG. 11D the transition portionof the wound treatment device 10 forms a shaped flexion joint or formedexpansion joint which stores “material” in a pleat, convolution orbellows or the like. This type of structure provides a means forexpanding the size of the transition portion to minimize the transfer offorces from the attachment portion 12 to the wound treatment portion 14.

FIG. 12A through FIG. 14B should be considered together. In theseembodiments of the invention the standoff structure reduces in height toresult in the increased transition portion area during the stretching ofthe wound treatment device.

FIG. 12A shows a part of a wound treatment device having a foam ringstandoff 15 which is shown in the unstressed or relaxed state. In thisinstance the transition portion projected area 17 is proportional todimension 88. In FIG. 12B the wound treatment device has been stretchedand the height of the foam ring standoff 15 is reduced in the Zdirection which has increased the transition portion projected area asrepresented by dimension 91.

FIG. 13A shows a part of a wound treatment device having a serrated cupstandoff 34 which is shown in the unstressed or relaxed state. In thisinstance the transition portion projected area 17 is proportional todimension 98. In FIG. 13B the wound treatment device has been stretchedand the height of the serrated cup standoff 34 is reduced in the Zdirection. The serrated wall sections splay out to permit the heightreduction which has increased the transition portion projected area asrepresented by dimension 99.

FIG. 14A shows a part of a wound treatment device having a foam ringstandoff 15 which is shown in the unstressed or relaxed state. Howeverin this construction the attachment portion 12 and transition portionmembrane 96 lie entirely in the first plane 56. In this instance thetransition portion projected area 17 is proportional to dimension 94. InFIG. 14D the wound treatment device has been stretched and the height ofthe foam ring standoff 15 is reduced in the Z direction. This heightreduction which has increased the transition portion projected area isrepresented by dimension 92.

FIG. 15 shows a version of the wound treatment device 10 which includesa dome shaped or hemispheric wound cover 19. At least a portion of thisdevice lies in the second XY plane 58.

FIG. 16 shows a version of the wound treatment device 10 which includesa releasable and resealable wound cover 20. To facilitate access to thewound the wound cover 20 may have a tab 29 located at the periphery ofthe wound cover 20. In general a reusable adhesive 30 may be applied tothe periphery of the wound cover 20 as well to allow the cover to bereleasable attached to the standoff 15 structure or composite shell 38.

FIG. 17A shows a releasable wound cover incorporating a heater pocketcover 21. In use the resealable wound cover 20 and pocket cover 21 formsa space for the heater 32.

FIG. 17B shows that one advantage of the resealable and removableconstruction is that the opening for the heater may be shifted withoutremoving or repositioning the wound treatment device 10.

FIG. 17C shows a wedge shaped wound treatment device 10. A line 31 inthe XY plane 11 of the attachment portion 12 intersects with a line 33which lies across the top of the standoff 15. These tow lines may meet apoint 35 in space as seen in the drawing.

FIG. 18 shows a an alternate method of attaching the planar heater 32 tothe wound cover 20. In this embodiment the heater has a hook or loopmaterial 37 attached to the edge of the heater 32 and the complimentaryloop or hook material 39 is attached tot he composite shell 38. In thisembodiment the wound cover need not be accessible to reorient the heater32. It should be appreciated that an adhesive may be used to attach theheater as well.

FIG. 19A is a perspective view of an alternate version of the woundtreatment device with a heater. In this embodiment the heater 83 is domeshaped to conform to the shape of the wound cover 84. complimentary loopand hook material 37 and 39 may be used for releasable attachment to thewound treatment device.

FIG. 19B is a perspective view of an alternate version of the woundtreatment device with a heater attached to the wound treatment devicewith an adhesive or the like. In this embodiment a resistive heater gridis formed in the cover to generate heat in response to electrical energyapplied trough leads 50.

FIG. 20A is a perspective view of an alternate version of the woundtreatment device with a dome shaped heater 86. In this embodiment theheater 86 has a collection of independent parallel connected resistiveloops typified by loop 87. In use the resistance of the loop is selectedto ensure that the radiated heat is uniform as measured at the woundsurface.

FIG. 20B is a perspective view of an alternate version of the woundtreatment device with a dome shaped heater 86 attached to the woundtreatment device 10.

FIG. 21A is a perspective view of an alternate version of the woundtreatment device with a dome shaped heater 89. In this embodiment aheater wire is coiled to provide the heater element.

FIG. 21B is a perspective view of an alternate version of the woundtreatment device with a dome shaped heater 89. In use the coil spacingindicated by dimension 87 can be adjusted to provide uniform heating ofthe wound area.

FIG. 22A is a perspective view of a wound treatment device 10 having twocomplimentary pockets shown as pocket 97 and pocket 95 which cooperatewith tab 83 and tab 75 formed on the heater 32.

FIG. 22B is a perspective view which shows tab 75 and tab 83 insertedinto the complimentary pockets 95 and pocket 97 to position and retain aplanar heater structure.

Having thus described the invention it should be apparent that numerouschanges may be made without departing from the scope of the invention asdefined by the claims.

What is claimed is:
 1. A wound treatment device, comprising: a woundtreatment portion including: a standoff for resting on skin, a surfaceon the standoff and an opening through the surface; and a cover actingagainst the surface of the standoff and forming a treatment volume withthe opening; an attachment portion; a heater; a heater connection on thewound treatment portion for retaining the heater over the openingagainst the treatment volume; and a compliant transition portionconnecting the attachment portion to the wound treatment portion.
 2. Thewound treatment device of claim 1, wherein the heater connection is hookand eye material.
 3. The wound treatment device of claim 1, wherein theheater connection is adhesive material.
 4. The wound treatment device ofclaim 1, wherein the heater includes tabs, the heater connectionincluding slots in the wound treatment portion for receiving the tabs.5. The wound treatment device of claim 1, wherein the wound cover isdome shaped and the heater is dome shaped.
 6. The wound treatment deviceof claim 1, wherein the wound cover is releasably attached to thetransition portion.
 7. The wound treatment device of claim 1, whereinthe wound cover is releasably attached to the standoff.